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@INPROCEEDINGS{Solokha:891662,
author = {Solokha, V. and Groth, M. and Brezinsek, S. and Brix, M.
and Corrigan, G. and Guillemaut, C. and Harting, D. and
Jachmich, S. and Kruezi, U. and Marsen, S. and Wiesen, S.},
title = {{T}he isotope effect on the detachment density in
{JET}-{ILW} {O}hmically confined plasmas},
reportid = {FZJ-2021-01648},
year = {2021},
abstract = {The isotope effect on the detachment density in JET-ILW
Ohmically confinedplasmasV Solokha1, M Groth1, S
Brezinsek2, M Brix3, G Corrigan3, C
Guillemaut4, D Harting3,S Jachmich5, U
Kruezi6, S Marsen7, S Wiesen2 and JET
contributors∗1 Aalto University, P.O. Box 14100,
FI-00076, Aalto, Espoo, Finland2 Forschungszentrum Julich
GmbH, Institut fur Energie- und Klimaforschung, IEK-4 -
Plasmaphysik, 52425 Julich, Germany3 EUROfusion Consortium,
JET, Culham Science Centre, Abingdon, OX14 3DB, UK4
Instituto de Plasmas e Fusao Nuclear, Instituto Superior
Tecnico, Lisbon, Portugal5 Ecole Royale Militaire School, Av
de la Renaissance 30, Brussels, Belgium6 ITER Organization
Route de Vinon sur Verdon, Saint Paul-lez-Durance, France7
Max-Planck-Institute for Plasma Physics, Greifswald,
Germany∗ See the author list of E. Joffrin et al. accepted
for publication in Nuclear Fusion Special Issue
2019,https://doi.org/10.1088/1741-4326/ab2276Studies in JET
with the ITER-like wall (JET-ILW) Ohmic plasmas show that
the density range, in which thepartial detachment at both
divertor targets is accessible, is affected by the hydrogen
isotope species as well asby the divertor geometry. These
studies are consistent with previous research showing that
the detachmentonset density for different hydrogen species
in JET with the carbon wall (JET-C) scales inversely with
the ionmass for vertical target (VT) configuration L-mode
discharges [1].The isotope effect on the detachment density
was reassessed for hydrogen and deuterium plasmas in
thevertical and horizontal target (HT) configurations. The
density of the detachment onset in the HT configurationfor
the deuterium discharges is $10\%$ lower than for the
hydrogen at the outer target (OT), while in the
VTconfiguration the isotope effect is stronger $(30\%)$ and
affects detachment onset density at both targets.Simulations
with the EDGE2D-EIRENE code [2,3] showed that the deuterium
cases have a $50\%$ higher neutraldensity than the hydrogen
cases due to the subdivertor entrance conductance dependence
on the thermalvelocity of the molecules. The increased
neutral densities in the deuterium cases cause two times
higherradiation losses in the simulations, while in the
experiments bolometry measurements showed only $30\%$
higherradiation losses. On the other hand, the Balmer-alpha
emission profiles across the outer divertor plate
aremeasured similar in shape and magnitude. Due to the
pumping plenum, which reflects $80\%$ of the
incidentparticles, and subdivertor geometry of JET, the
probability of the recycled particles from the inner target
(IT) toreach the cryopump via the IT subdivertor entrance is
close to zero. The poloidal ExB drift direction affects
themagnitude of the isotope effect by moving particles from
the OT to the IT in the normal BT direction
(weakerisotope effect) or towards the OT and the cryopump in
the reversed BT configuration (stronger isotope
effect). Inthe HT configuration, the molecules at the IT can
not be pumped, whereas in the VT configuration moleculesfrom
both targets could be pumped due to connection to the OT
subdivertor entrance by the private flux region.The higher
detachment onset densities for heavier isotope species
caused by the higher molecular densities.The dependence of
molecular transport on the strike-point (SP) position due to
the curvature of the target platesis predicted to cause the
higher detachment onset densities in cases with higher
strike-point positions. Theusage of the low SP position
decreases the detachment onset density and increases pumping
efficiency, whichleads to better particle control as well as
to a bigger influence of the subdivertor entrance
conductance andisotope species on the divertor plasma.[1]
C.F. Maggi et al, Nucl. Fusion 39 979 (1999).[2] R. Simonini
et al, Contrib. Plasma Physics, 34 (1994), 368-373.[3] S.
Wiesen, JET ITC-Report, (2006), http://www.eirene.de/e2deir
report 30jun06.pdfCorresponding author: tel.:
+358(40)257-44-98, e-mail: vladimir.solokha@aalto.fi
(V. Solokah)},
month = {Jan},
date = {2021-01-25},
organization = {24th International Conference on
Plasma Surface Interactions in
Controlled Fusion Devices (PSI 2020),
virtuell (virtuell), 25 Jan 2021 - 29
Jan 2021},
cin = {IEK-4 / IBI-1},
cid = {I:(DE-Juel1)IEK-4-20101013 / I:(DE-Juel1)IBI-1-20200312},
pnm = {134 - Plasma-Wand-Wechselwirkung (POF4-134)},
pid = {G:(DE-HGF)POF4-134},
typ = {PUB:(DE-HGF)1},
url = {https://juser.fz-juelich.de/record/891662},
}
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